<pclass="note"><strong>Optional: </strong> Add <strong><code>{{ page.spdx-id }}{% if xgpl %}-or-later{% endif %}</code></strong>{% if xgpl %} (or <strong><code>{{ page.spdx-id }}-only</code></strong> to disallow future versions){% endif %} to your project's package description, if applicable (e.g., <ahref="https://docs.npmjs.com/files/package.json#license">Node.js</a>, <ahref="http://guides.rubygems.org/specification-reference/#license=">Ruby</a>, and <ahref="https://doc.rust-lang.org/cargo/reference/manifest.html#package-metadata">Rust</a>). This will ensure the license is displayed in package directories.</p>